Water Craft With a Buoyancy Body

ABSTRACT

The invention relates to a water craft with a preferably closed buoyancy body ( 1 ), a propulsion motor ( 2 ), arranged within the buoyancy body and a propulsion fin ( 14 ), driven by the propulsion motor, designed to generate drive by means of a reciprocating movement. An efficient close to natural movement of the water craft is possible, wherein the propulsion fin ( 14 ) comprises an elastic retainer body ( 6 ), fixed to the buoyancy body ( 1 ) at a joint and an attachment point is provided at a given distance from the joint ( 16 ) which is engaged by an operating mechanism to exert a torque on the retainer body ( 6 ).

The invention relates to a water craft with a buoyancy body, a propulsion motor arranged within the buoyancy body, and a propulsion fin which is driven by the propulsion motor and arranged to generate a propulsive force by means of a reciprocating movement, with the propulsion fin comprising an elastic retainer body fixed to the buoyancy body at a joint, and with a point of application being provided on the retainer body at a predetermined distance from the joint.

The propulsion of water craft can occur in different ways. Drives via propellers are usually provided, which are easy to realize and are efficient. The disadvantageous aspect in this embodiment is the likelihood of injury caused by the rotating propeller when people come into its sphere of action. For this reason, auxiliary drives for surfboards or similar water craft that use propellers have not prevailed on the market.

Water craft are known from DE 297 20 003 U and U.S. Pat. No. 4,172,427 A as well as U.S. Pat. No. 4,345,903 A which comprise a drive apparatus which generates a propulsive force by means of a movable fin. Such drive fins have a relatively low efficiency as a result of their simple kinematics and their flow resistance, and make the water craft bulky and susceptible to damage.

A fin-like ship drive is known from SU 529 104 A which comprises an elastic fin. The tip of the fin is held in an articulated manner relative to a root of the fin. The movement at this joint occurs passively however. The driving power of such a drive is therefore limited.

U.S. Pat. No. 3,874,320 A also shows a fin-like ship drive whose fin can be made to oscillate via an eccentric mechanism. The efficiency of this drive apparatus is also insufficient.

Further fin-like ship drives are known from DE 196 23 038 A, U.S. Pat. No. 5,163,857 A and GB 1 583 292 A. The disadvantages as explained above also apply to these known apparatuses.

It is the object of the present invention to provide a water craft which avoids these disadvantages and enables especially to be used without any disadvantages in a non-driven state such as a surfboard for example as well as in a driven state. A simple configuration and sturdy solution shall be achieved which in addition has an appealing design and is functional.

These objects are achieved in accordance with the invention in such a way that an actuating mechanism attacks at the point of application in order to exert a torque on the retainer body.

The relevant aspect in the present invention is that not only the drive motor but the entire drive apparatus is integrated in a buoyancy body optimized in respect of flow, and that the kind of actuation ensures realizing not only a simple oscillating motion of an otherwise rigid fin, but also generating a complex fish-like oscillating motion. It is ensured in this way that in the non-driven state the water craft has full functionality of its original function (e.g. as a surfboard) without having any limiting add-ons or appurtenances. High efficiency is achieved in the driven state and likelihood of injury is minimized, even when a swimmer comes into direct contact with the moving water craft.

The buoyancy body is preferably enclosed, such as is the case with a surfboard for example. It is alternatively also possible to realize water craft with partly or fully open buoyancy bodies. An aggregation of several inventive elements is also possible, such that a water craft is realized in the manner of a catamaran with two buoyancy bodies or a float with several buoyancy bodies.

It has been noticed that it is especially advantageous when a reciprocating oscillating motion of the propulsion fin is superimposed with a wave-like deformation. Said wave-like deformation is achieved in that a torque is applied locally at least at one point of the propulsion fin.

A mechanically especially simple and cost-effective solution for applying the torque can be realized by a toothed belt. A driving chain can be provided in an alternative way. It is especially advantageous when said toothed belt or driving chain is in engagement with a first gearwheel which is rigidly connected with the buoyancy body. A further gearwheel is fastened in this case to the joint of the elastic retainer body and is used there for introducing the torque as described above. A belt sprocket is designated here and below as a gearwheel in order to maintain clarity of the illustration.

It is also possible within the terms of the invention that the actuating mechanism comprises a cardan shaft. Especially large forces and moments can be transmitted in this way.

An especially simple, robust and highly effective embodiment of the water craft in accordance with the invention provides that the actual drive mechanism is mechanically independent of the actuating mechanism which introduces the torque into the propulsion fin.

It is especially advantageous when the buoyancy body comprises a support structure which consists of rigid sections and is covered by covering which is at least partly flexible. An especially simple arrangement and cost-effective production can thus be ensured. It is especially advantageous in this respect when the sections of the support structure are connected in the area of the fin via joints with the other sections of the support structure. Kinematics of the fin motion can thus be optimized with respect to the highest possible efficiency.

The drive motor may be arranged within the terms of the invention both as an electromotor as well as an internal combustion engine. In the first case, power sources to be considered are storage batteries, fuel cells and/or solar panels. The electromotor per se can be arranged as a stepper motor, servomotor, synchronous motor, asynchronous motor or the like. In the second case, petrol, diesel fuel or hydrogen can be used as a power source.

An especially elegant and versatile solution can be achieved in such a way that a main section of the buoyancy body is provided with a flat arrangement, so that in the used position the width is larger than the height and the fin is arranged substantially perpendicular relative to the same, so that in the used position the height is larger than the width. The main body corresponds substantially to a conventional surfboard, whereas the fin is arranged in the manner of a fin of a fish.

An especially harmonious fin motion can be achieved in such a way that several joints arranged behind one another are provided for movably holding the fin.

Preferably, the individual components which are connected by joints are each controllable through belt drives in order to enable influencing the joint movement.

An especially preferred embodiment of the invention provides a stored program control in which various motion patterns are stored. It concerns a drive-off motion for example which is characterized by a continuously and smoothly rising speed and further a rapid acceleration, a gliding phase and the like. Moreover, the curve radius can be variably pre-programmed between a sharp turn and a smooth change of direction.

The present invention is now explained in closer detail below by reference to embodiments shown in the drawings, wherein:

FIG. 1 schematically shows a top view of a water craft in accordance with the invention;

FIG. 2 shows a sectional view along line II-II in FIG. 1;

FIG. 3 shows a further embodiment of the invention in a top view;

FIG. 4 shows a further embodiment of the invention in a view according to FIG. 3 in an alternative position;

FIG. 5 shows a detail of an embodiment which is similar to that of FIG. 1;

FIG. 6 shows a sectional view along line VI-VI in FIG. 5;

FIG. 7 shows a detail of FIG. 4, and

FIG. 8 shows a sectional view along VIII-VIII in FIG. 7.

The water craft of FIG. 1 consists of a buoyancy body 1, in the interior of which a drive motor 2 is provided which is arranged as an electric stepper motor. Drive motor 2 drives a first pulley 4 via a first V-belt 3, which pulley drives a second V-belt 5 on its part. Alternatively, it is also possible to provide a reduction gear (not shown here). A further pulley 7 is fastened to an elastic retainer body 6, so that an oscillating motion of the retainer body 6 can be introduced in the direction of arrows 15 a, 15 b by a reciprocating rotating of the drive motor 2. The retainer body 6 is connected at a joint 17 with the buoyancy body 1 which is situated approximately in the area of the pulley 4. A first gearwheel 8 is further rigidly connected at this point with the buoyancy body 1, with a toothed belt 9 being wrapped around said gearwheel which extends further to a second gearwheel 10 which is rigidly connected with the retainer body 6 in the area of the point of application 16. When an oscillating motion of the retainer body 6 is caused in the direction of arrows 15 a, 15 b by the drive motor 2, a torque is introduced into the retainer body 6 at the same time via the toothed belt 9. The point of introduction is the one of the fastening of the second gearwheel 10, i.e. the point of application 16. The direction of the torque is marked with the arrows 18 a, 18 b. It is clearly shown that in the case of an oscillating motion in the counter-clockwise direction (arrow 15 a) a torque is caused in the clockwise direction (arrow 18 b). It is ensured in this way that the retainer body 6 performs a wave-like motion conducive to flow.

The buoyancy body 1 and the holding body 6 are covered by a common covering 11. The power supply of the drive motor 2 occurs through rechargeable batteries 12. A display and control field 13 is used for monitoring and influencing the water craft.

The driving direction can be influenced especially through purposeful control of the propulsion fin 14. A starboard course can be set for example by moving the propulsion fin 14 back and forth only between the plane of symmetry and the extreme position on the starboard side.

FIG. 2 shows the arrangement of the buoyancy body 1 plus propulsion fin 14 in a vertical sectional view.

FIGS. 3 and 4 show an embodiment in which a fixed gearwheel 8 is arranged concentrically to a joint 17 of a first lever 20. A further gearwheel 10 is attached to a further one 16 and a further lever 21 is linked. An end lever 22 is attached to a further joint 23, which lever forms the retainer body 6 together with the first lever 20 and the further lever 21.

FIG. 4 shows that in this embodiment it is possible to generate an even more fluid wave oscillation of the propulsion fin 14.

FIG. 5 shows an embodiment in which the propulsion motor 2 is attached to a first lever 20 and swivels simultaneously with the same. The pinion 24 of the propulsion motor 2 drives a cylinder gear 25 which drives the further gearwheel 10 via a further cylindrical gear 26, 27, which finally exerts the required torque on the first lever 20 via the toothed belt 9. The further lever 21 is rigidly connected with the further gearwheel 10 and swivels accordingly with the same.

The embodiment of FIG. 7 and FIG. 8 corresponds in a first section substantially to the solution as described above, with a first propulsion motor 2 a driving a first toothed belt 9 a via various cylinder gears 24, 25, 26 and 27. The difference is that it is not the further lever 21 but a third gearwheel 28 which is connected with the further gearwheel 10, which third gearwheel drives a second toothed belt 9 b. It is guided at its downstream end about a fourth gearwheel 29 which is driven by a second drive motor 2 b and an analogue gearing consisting of the cylinder gears 30, 31, 32 and 33. The propulsion motor 2 b is attached to the second lever 21.

A flowing motion can thus be realized, as is shown in FIG. 4.

The present invention allows providing an efficient and natural mode of movement for a water craft. 

1. A water craft, comprising a buoyancy body (1), a propulsion motor (2) arranged within the buoyancy body, and a propulsion fin (14) which is driven by the propulsion motor (2) and arranged to generate a propulsive force by means of a reciprocating movement, with the propulsion fin (14) comprising an elastic retainer body (6) fixed to the buoyancy body (1) at a joint (17), and with a point of application (16) being provided on the retainer body (6) at a predetermined distance from the joint (17), wherein an actuating mechanism attacks at the point of application (16) in order to exert a torque on the retainer body (6).
 2. A water craft according to claim 1, wherein the actuating mechanism comprises a toothed belt (9).
 3. A water craft according to claim 1, wherein the actuating mechanism comprises a driving chain.
 4. A water craft according to claim 2, wherein the toothed belt (9) is in engagement with the first gearwheel (10), which is rigidly connected with the buoyancy body (1).
 5. A water craft according to claim 1, wherein the actuating mechanism comprises a cardan shaft.
 6. A water craft according to claim 1, including a drive mechanism for the retainer body (6) which introduces a force into the retainer body (6) in the area of the point of application in order to cause an oscillating motion.
 7. A water craft according to claim 1, wherein the actuating mechanism is mechanically independent of the drive mechanism for the retainer body (6).
 8. A water craft according to claim 1, wherein the propulsion fin (14) forms an integral component of the buoyancy body (1).
 9. A water craft according to claim 1, wherein the drive mechanism for the retainer body (6) comprises a cable pull.
 10. A water craft according to claim 1, wherein the buoyancy body (1) comprises a support structure consisting of rigid sections and is covered jointly with the propulsion fin (14) by an at least partly flexible covering (11).
 11. A water craft according to claim 1, wherein a main section of the buoyancy body (1) is provided with a flat arrangement, so that in the used position the width is larger than the height and that the fin is arranged substantially perpendicular to the same, so that in the used position the height is larger than the width.
 12. A water craft according to claim 1, wherein the water craft is arranged as a surfboard and comprises a fixing device for a sail.
 13. A water craft according to claim 1, wherein the drive motor (2) is an electromotor.
 14. A water craft according to claim 1, wherein the drive motor (2) is an internal combustion engine.
 15. A water craft according to claim 1, wherein several joints arranged behind one another are provided for movable bearing of the fin which is actuated by several drive motors (2).
 16. A water craft according to claim 15, wherein the motion of the components connected by several joints can each be controlled via belt drives.
 17. A water craft according to claim 1, wherein a programmable logical controller is provided, through which the various motion patterns can be set.
 18. A water craft according to claim 1, wherein the propulsion fin (14) has a braking position.
 19. A water craft according to claim 1, wherein the buoyancy body (1) is provided with a closed configuration.
 20. A water craft according to claim 1, wherein a vertical pivoted joint is additionally provided.
 21. A water craft according to claim 1, wherein the buoyancy body has a fish-like shape and therefore its flow prerequisites for generating propulsion and change of direction are achieved to a high extent.
 22. A water craft according to claim 1, wherein several buoyancy bodies (1) with a propulsion fin (14) each are provided.
 23. A water craft according to claim 22, wherein the propulsion fins (14) of several buoyancy bodies (1) have a common drive motor (2).
 24. A water craft according to claim 3, wherein the driving chain is in engagement with the first gearwheel (10), which is rigidly connected to the buoyancy body (1). 